title: Double-tailed lipid modification as a promising candidate for oligonucleotide delivery in mammalian cells.
abstract: BACKGROUND
  The potential use of nucleic acids as therapeutic drugs has triggered the quest for oligonucleotide conjugates with enhanced cellular permeability. To this end, the biophysical aspects of previously reported potential lipid oligodeoxyribonucleotide conjugates were studied including its membrane-binding properties and cellular uptake.
  
  
  METHODS
  These conjugates were fully characterized by MALDI-TOF mass spectrometry and HPLC chromatography. Their ability to insert into lipid model membrane systems was evaluated by Langmuir balance and confocal microscopy followed by the study of the internalization of a lipid oligodeoxyribonucleotide conjugate bearing a double-tail lipid modification (C28) into different cell lines by confocal microscopy and flow cytometry. This compound was also compared with other lipid containing conjugates and with the classical lipoplex formulation using Transfectin as transfection reagent.
  
  
  RESULTS
  This double-tail lipid modification showed better incorporation into both lipid model membranes and cell systems. Indeed, this lipid conjugation was capable of inserting the oligodeoxyribonucleotide into both liquid-disordered and liquid-ordered domains of model lipid bilayer systems and produced an enhancement of oligodeoxyribonucleotide uptake in cells, even better than the effect caused by lipoplexes. In addition, in β2 integrin (CR3) expressing cells this receptor was directly involved in the enhanced internalization of this compound.
  
  
  CONCLUSIONS
  All these features confirm that the dual lipid modification (C28) is an excellent modification for enhancing nucleic acid delivery without altering their binding properties.
  
  
  CONCLUSIONS
  Compared to the commercial lipoplex approach, oligodeoxyribonucleotide conjugation with C28 dual lipid modification seems to be promising to improve oligonucleotide delivery in mammalian cells.
authors.affiliation: Department of Biochemistry and Molecular Biology, UPV/EHU and Biophysics Unit, Leioa, Spain.
authors.forename: Begoña
authors.initials: B
authors.lastname: Ugarte-Uribe
authors.forename: Santiago
authors.initials: S
authors.lastname: Grijalvo
authors.forename: Jon V
authors.initials: JV
authors.lastname: Busto
authors.forename: César
authors.initials: C
authors.lastname: Martín
authors.forename: Ramón
authors.initials: R
authors.lastname: Eritja
authors.forename: Félix M
authors.initials: FM
authors.lastname: Goñi
authors.forename: Itziar
authors.initials: I
authors.lastname: Alkorta
mesh_terms: D001483:Base Sequence; D002851:Chromatography, High Pressure Liquid; D017931:DNA Primers; D005456:Fluorescent Dyes / Q000737:chemistry; D006367:HeLa Cells; D006801:Humans; D008051:Lipid Bilayers; D008055:Lipids / Q000737:chemistry*; D018613:Microscopy, Confocal; D009841:Oligonucleotides / Q000008:administration & dosage* / Q000737:chemistry; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D017931:DNA Primers; D005456:Fluorescent Dyes; D008051:Lipid Bilayers; D008055:Lipids; D009841:Oligonucleotides
keywords: 1,2-dioleyl-l-α-phosphatidylcholine; ACN; AFM; CPG; Cellular uptake and localization; Chol; DMEM; DOPC; Dulbecco's modified Eagle's medium; FBS; GMFI; GUV; Geometric Mean Fluorescence Intensity; L(d); L(o); LOC; Lipid oligonucleotide conjugates; MLV; Model membrane systems; ODN; PBS; PFA; SPB; SUV; TEAA; TLC; TOF; acetonitrile; atomic force microscopy; cholesterol; controlled-pore glass; eSM; egg sphingomyelin; fetal bovine serum; giant unilamellar vesicle; lipid oligonucleotide conjugate; liquid-disordered; liquid-ordered; multilamellar vesicle; oligodeoxyribonucleotide; paraformaldehyde; phosphate-buffered saline; small unilamellar vesicle; supported planar bilayer; thin-layer chromatography; time-of-flight; triethylammonium acetate